Bobbin



Nov. 18,*1958 D. VAN KATWIJK Y 2,850,843

BoBBIN Filed sept. 301 1954 ffy-2.

United States Patent O BoBBlN Dirk van Katwijk, Velp, Netherlands Application September 30, 1954, Serial No. 459,259 3 Claims. (cl. 24a-118.3)

This invention-relates to a tubular core or bobbin on which yarn, threads, filaments and the like may be wound and unwound.

Cores for the above purpose are made from paper strip convolutions with an intervening adhesive or impregnating medium, the whole thereafter being impregnated.

These cores are usually shaped externally like a truncated cone having a small apex angle. The wall of the core is generally of uniform thickness throughout. The lower and, if desired, the upper edge of the core may be provided with reinforcements.

It is generally known to provide the core with an impressed, helical groove to facilitate the winding on of the yarn. The helix runs as in an ordinary single-thread screw having a right-handed, square thread.

The width of the thread is about one half of the thread pitch and the depth of the thread is generally of the order of 0.5 mm. With this depth thread, the width of the groove is of the order of a few millimetres.

It is further usual to start and finish the yarn a few centimetres from the ends of the core.

After the yarn has been wound onto the core, the wound cores are conveyed to the weaving mill where the yarn is kinkedly withdrawn from the cores.

In this operation definite forces are exerted on the yarn and their limit determines the maximum speed at which the yarn can be withdrawn from the cores.

Experience has shown that the maximum speed is 600- 700 yards per minute (9-11 m./sec.). If an attempt is made to increase the speed still further, this leads to breaking of the yarn.

In a surprising manner experiments have yshown that the unwinding speed can be increased to about double the normal if, in accordance with the invention, the bottom and, if desired, the walls of the helical groove isy not smooth as hitherto but is made uneven.

With cores according to this invention it is possible to achieve unwinding speeds up to 1200 yards per minute A(18 metres per second).

It has been shown experimentally that the provision of straight fiutes on the bottom of the helical groove is very favourable, especially if the fiutes are disposed at such an angle to the groove and axis of the core that the flutes of the various grooves appear to form together a subdivided multiple thread screw having left hand threads of considerably large pitch.

In the accompanying drawings:

Fig. l is an elevational View of a core according to a preferred embodiment of this invention,

Fig. 2 is a fragmentary cross sectional view of part of a core according to Fig. l, taken on line 2 2 of Fig. 1, and

Fig. 3 is an elevational fragmentary view of the lower part of a core according to Fig. l, showing the drawing off of the yarn.

The core according to this invention comprises a frustoconical body 1 made by wrapping and impregnating paper. A homogeneous entity is obtained by impregna# tion, for example with an artificial resin. The core ends 2, 3 are rounded. The cores have a helically formed groove obtained by a grooving operation. The helical groove terminates in an upper annular part 5 anda lower annular part 6. Adjacent thereto are rsmooth parts 7, 8.

2,860,843 Patented Nov. 18, 1958 ice The top of upper part 7 merges into the rounded part 2. The inner surface of the core is smooth and is of conical shape.

The bottom of the groove 4 (the so-called fiat relief embossing) is not smooth but is provided with corrugations such as flutes 9.

These flutes comprise small elevations and may be obtained for example by a grooving operation. The height of the iiutes is less than the depth of the groove, see Fig. 2.

The flutes form With the axis of the core an angle of notmore than 15, disposed in a different plane from the angle formed between the groove and said axis. The flutes disposed above one another in the various grooves form a left-handed screw thread as shown by the dot and y the direction of the arrow. It appears that at the arc 11,

where the yarn does not as yet move accurately in the longitudinal direction but moves to the left around the core, the infiuence of the flutes is at a maximum.

It is further apparent that the illustrated form of the flutes is only an example of unevenness applied to the base of the groove or grooves. This unevenness may also consist of small swellings, small cavities and the like surface irregularities.

It is also within the scope of the invention to provide, in certain cases, also the walls of the groove or grooves with uneven surfaces.

I claim: 1. A tubular bobbin, for use in winding filament material, saidbobbin having an external helical groove, the bottom surface of said groove having substantially parallel flutes, each flute forming a small angle with a line defined on said bottom surface by the intersection of a plane coinciding with the axis of the bobbin.

2. A tubular bobbin, for use in winding filament material, said bobbin having an external helical groove, the bottom surface of said groove having substantially parallel flutes, each flute forming a small angle not exceeding 15 with a line defined on said bottom surface by the intersection of a plane coinciding with the axis of the bobbin.

3. A tubular bobbin, for use in winding filament material, said bobbin having an external helical groove forming a normal righthanded screw thread, the bottom surface of said groove having substantially parallel flutes, each flute forming a small angle with a line defined on said bottom surface by the intersection of a plane coinciding with the axis of the bobbin, the longitudinal direction of said flutes being such that if lines are drawn through a point of a flute ofrwhich the first is parallel to the flute, the second is parallel to the axis of the bottom and the third is parallel to the helical groove immediately adjacent said flute, the smallest angle between said first and second lines and the smallest angle between said second and third lines are disposed on opposite sides of a plane coinciding with said axis and with said second line.

References Cited in the file of this patent UNITED STATES PATENTS 359,447 Keene Mar. 15, 1887 468,567 Krantz Feb. 9, 1892 974,126 Daniell Nov. 1, 1910 974,127 Daniell et al Nov. 1, 1910 2,163,618 Muller lune 27, 1939 2,297,208 Fallscheer Sept. 29, 1942 2,336,086 Goldman Dec. 7, 1943 FOREIGN PATENTS 214,192 Switzerland July l, 1941 

